Formulations having an acidic pH, (i.e., <7), containing cationic components, such as cationic surfactants and salts thereof or active acidic components are commonly referred to as “low pH” formulations. Stable low pH viscous emulsion and gel formulations are difficult to obtain. Most commonly used thickeners are synthetic associative thickeners that are frequently anionic and hence typically are incompatible with the cationic component, especially quaternary ammonium salts, or are ineffective thickeners at low pH.
Consequently, the formulator of low pH compositions, especially emulsions, has a limited choice of either nonionic thickeners, such as nonionic surfactants, or cationic thickeners. Nonionic thickeners are uncharged and thus are assumed to be less reactive, but nonionics tend to inactivate preservatives and in some cases promote microbial growth. While some cationic polymeric rheology modifiers, such as hydrophobically modified aminoacrylate copolymers, are available commercially, their rheological properties are unpredictable, or aesthetically unsatisfactory.
Thus, there is an ongoing need and desire for a cationic compatible polymeric rheology modifier for low pH formulations.